Clutch.



0. G. PFEIFFER.

CLUTCH.

APPLICATION FILED NOV. 20. 1911.

Patented Sept. 14, 1915.

2 SHEETS-SHEET l.

0. G. PFEIFFER.

CLUTCH.

APPLICATION FILED NOV. 20. IBM.

Patented Sept. 14, 1915.

2 SHEETSSHEET 2.

I therefore reduces the capacity of O TTO Gr. PFEIFFER, SALT LAKE CITY,UTAH,

COMPANY, OF SALT LAKE CITY, UTAH,

ASSIGNOR TO UTAHNA DEVELOPMENT A CORPORATION OF UTAH.

CLUTCH.

Specification of Letters Patent.

Patented Sept. re, 1915.

Application filed November 20, 1911. Serial No. 661,384.

To all whom it may concern Be it known that I, OTTO Gr. Prmrrnu, acitizen of the United States, and residing at Salt Lake City, in thecounty of Salt Lake and State of Utah, have invented certain new anduseful Improvements in Clutches, of which the following is aspecification.

- This invention relates to clutches and more particularly to clutchesof the drum and expanding band or ring type.

In clutches of the expanding band or ring type, as heretoforeconstructed, the band shoe is pivoted at a fixed point with respect tothe spider or clutch member In expanding such a clutch the free end ofthe band is moved to expand the band to throw it into grippingengagement with the cylindrical surface on the drum. It is found howeverthat with such a construction the arc of contact between the band andthe drum will not include the entire circumferential surface of theband, in view of the fact that the end of the-band is fixed radially andcannot tional engagement with the drum. It isthus found that thegripping engagement will be a maximum at the free ends of the band andwill decrease as we proceed toward the point of attachment of the bandto its carrying spider. This construction obviously reduces thefrictional arc of contact very much and the clutch requiring a muchgreater gripping surface than if the gripping engagement or are wouldextend along the entire circumferential surfaces of the band and drum.Such a construction also causes .the free end to engage suddenly,therebyapplying the power with a jerk and preventing a gradualengagement or closing of the clutch, which is desirable especially inmotor vehicles.

The objects of this invention areth erefore to construct a clutch gripthe drum alongthe entire circumferential surface of the band and inwhich the gripping arc will extend uniformly for practically 360 andwhich is so constructed that it can be engaged gradually.

Further objects are to improve the clutch as to details, and furtherobjects will appear from the detail description taken in connection withthe accompanying drawings in which:

Figure 1 is a longitudinal section along carrying it.-

move freely into fricin which the band will the line 11 Fig. 2, Fig. 2is a section on the line 22 Fig. 1 showing the clutch mechanism inelevation and Fig. 3 is a section on the line 3-3 Fig. 2.

Referring to the accompanying drawings, 10 and 11 designate shaftseither of which may be the driving or driven shaft. In the specificconstruction shown the clutch is shown as applied to a motor vehicle, inwhich 10 will form the motor crank shaft supporting the fly wheel 12,and 11 the driven shaft connected to the usual change speed gearing. Thefly wheel web has cast thereon the clutch drum 13 which is machined tofurnish an inside friction surface. A spider 141' is keyed to the end ofshaft 11 and has its hub 15 supported in the fly wheel through a ballbearing 16. The clutch band or ring engaging the inner surface of thedrum comprises two similar shoes 17' each provided near its center withspaced lugs,

18 embracing the free ends of the spider arms. Bolts 19 pass through theears and through slots in the ends of the arms, so that each shoe willbe supported between its ends on the spider for a limited outward andinward movement at its point of attachment toward and from the drumsurface. One free end of each shoe is provlded with a lug 20 forming abearing for a lever 21 which is pivoted to the lug by a screw as shown.

The other free end of each shoe is provided with a lug 22 receiving anadjusting screw 23, and each of the levers 21 is provided with a toe 2dadapted to engage the end of the screw 23. Each lever 21-is' providedwith a laterally extending rounded end 25 adapted to be engaged bya'cone sleeve 26 loosely mounted upon the shaft 11.

The clutch is expanded by moving the cone sleeve to the left Fig.1.,thereby causing it to swing the levers 21 and spread the ends of theshoes 17 apart by the engagement of the toes 2 1 with the screws 23.When the cone sleeve is moved to the right the levers 21 will bereleased so as to permit the shoes to contractand move away from thedrum. In order however that this contracting movement be made morepositive, springs 2? connect the lugs 20 and 22 through screws or pins28, so that when the levers 21 are released by the cone sleeve thesprings will act topositively contract the clutch band.

The cone sleeve 26 may be operated to en equally and uniformly all Thisconstruction gage and disengage the clutch in any suitable manner. Inthe specific construction shown a shifting fork 29 is mounted on abracket 30 carried'by across member 31 of the motor vehicle chassis,which cross member also carries the bearing 32 for the shaft 11. Theshifting fork is operated through the usual clutch pedal 33 to releasethe clutch, while the clutch is thrown into engagement by a spring 34 onthe shaft 11 bearing at one endv against the coned sleeve 26 and at mentwith the friction surface of the drum when they are spread apart, andthis engagement will take place along the entire circumferentialsurfaces of the shoes, and

furthermore the engagement will take place along the shoes at theirpoints of attachment to the spider as well as at their free ends. Thecombined sliding and pivotal mounting of the shoes at their points ofsupport permits free movement of these shoes at their points of'supporttoward and from the inside surface of the drum. It will be noted thatthe lever 21:is pivoted on the free end of a shoe and engages a screw onthe abutting free end of the other shoe, and that this lever has a looseconnection The freeends of the shoes can therefore moveindependentlytoward and from' the drum and also slightly circumferentially of thedrum. This construction permits the clutch shoes to automaticallyadjust'themselves to the inside surface of the drum, for if theresistance offered by one shoe end is' less than that of the adjacentshoe, so that one will engage the friction surface before.

the other, the former shoe will become in turnv an abutment for thelever 21 to cause the other shoe to be thrown into frictional;

engagement. The connection between the actuatorfcone and the free endsof the clutch as to equalize the 'shoes into engagement shoes istherefore such movements of these with the drum and cause them to bearequally thereon. The clutch shoes will therefore bear uniformly againstthe drum surface along the entire lengths of the shoes. It willtherefore be seen that the arc of contact will be nearly andsubstantially 360. therefore results in high efficiency and low that thetotal friction surfaces are fully utilized. When the clutch shoes arethrown into engagement with the drum, the engage with the actuator cone26;

weight in view of the fact ment will take place first at the center ofthe shoes, or if at the ends, the engagement will be substantiallyuniform at both ends. It is found therefore that the engagement of theclutch can be made V ually apply the power. This is not possible with aconstruction in which one end only of the band engages first, since sucha construe-e tion will cause the engagement of the re maining portionwith a slap, thereby applying the power with a jerk. The levers 21 bearagainst the armslet and thus these arms gradually to gradwill take upthe thrust of the cone sleeve 26.

While the clutch is shown as applied to a motor vehicle, it is obviousthat its application is not-necessarily limited to that class of drive,but its application may be general. It is further obvious that variouschanges may be madein the details of construction without departing-fromthisinvention, and

it is therefore to be understood that this inventionis not to be limitedto the specific construction shown and described.

The invention is claimed broadly in my copending application SerialNumber 779,010, filed July 14, 1913. Y

Having thus described the invention what is claimed is: i

1. In a clutch, a pair of clutch members,

one of said clutch members having an inside friction surface, a pair offlexible band shoes adapted to expand and engage said friction surface,means for; supporting said shoes intermediate their ends on the otherclutch,

member, constructed to permit free movement of said shoes at theirpoints ofsupporttd Ward and from said friction surface, an armpivoted-onthe free end of each shoe and loosely engaging the adjacentend of the other shoe, and an actuator loosely engaging said arms,whereby said actuator is loosely connected to the free-ends of saidshoesfor expanding said friction surface,

movements 1' of said shoes into engagement with said friction surface:andf cause them to bear equally on said friction" surface. 2. In aclutch, a pair of clutch members, a

friction drum on oneof said members, a'

I and moving them iluniformlyf along their entire lengths radiallytoward and saidparts being no constructed and arranged to equalize the,

band shoe adapted-to expand and friction- V ally engage the insidesurface of said drum, an arm on the other clutch member, means forsupportingsaid shoe between its ends on levermounted on one of the freej shoe and bearing against said,

said arm, a ends of said arm, and a cam member for operating saidlever,.whereby said. arm supports said lever I i against the thrust ofsaid operatingcam member.

3. In a clutch, a a friction drum on one of said members, a plurality ofband shoes forming together a band or ring and pair of clutch members, I

adapted to expand and :Eri'otionally engage the inside surface of saidIn testimony whereof I affix my signature drum, arms on the other clutchmember, in presence of two Witnesses. means for supporting said shoesbetween OTTO G PFEIFFER their ends on said arms, levers mounted on 5 thefree ends of said shoes and bearing, at Witnesses:

their free ends, against said arms, and means J. H. BRUNINGA, foroperating said levers. A. H. ALMSTEDT.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. 0.

